MRI brain in the latest and advanced computer-based cross-sectional imaging modality provides both anatomical and physiological information of the brain. It is non-invasive, which means no radiation is involved. The brain is the most frequently imaged organ by Magnetic resonance imaging.
Indications for MRI brain
Patient preparation
Before preparation:
Take a complete history from the patient, if in case the indications are not clear referring physician should be contacted.
All the metallic and artifact-causing objects needed to remove.
Disposable earplugs should be provided to each patient to devoid the patient from repeated noise during scanning.
It is important to instruct the patient to avoid coughing or producing other large voluntary movements during or in between the scans.
Ensure the IV line prior to the pre-contrast acquisition preferably with IV cannula 20 or 22 gauzes.
Contrast media
Gadolinium-based contrast media is given to enhance is useful in brain imaging. It is often believed that the contrast media (gadolinium) is indicated for all the lesions.
IV- Gadolinium: 0.1-0.2 mmol/kg of body weight
-is given as a bolus at the rate of 1ml/sec.
-like a slow infusion at a rate of 1ml/sec.
Prepare the head coil.
Patient position:
The patient lies in the supine position with the head first.
Topogram positioning / Landmark- Center the FOV on the glabella in the midline.
MRI Brain Protocols
Routine brain Protocol
Sequence-
– Scout: 3 plane localizers
– T2 FSE in the axial plane
– T2 FLAIR in the axial plane
– T1 SE in the sagittal plane & coronal plane
– DW EPI based in the axial plane
– Post-contrast – T1 SE in the axial plane and coronal plane
Axial sequence
T1 weighed
T2 weighed
Signal intensities seen | CSF | FAT | White matter | Grey matter | Bleed | Gadolinium |
T1 | DARK | BRIGHT | BRIGHT | DARK | BRIGHT | BRIGHT |
T2 | BRIGHT | DARK | DARK | BRIGHT | BRIGHT | DARK |
FLAIR
Advantages of FLAIR:
Sagittal Sequence
Coronal sequence
Diffusion-Weighted sequence